


What to Do with a Demon

by Kendrickhier



Category: Supergirl (TV 2015)
Genre: Demon AU, F/F, includes Non & Kara
Language: English
Status: Completed
Published: 2017-11-12
Updated: 2017-11-12
Packaged: 2019-01-31 12:11:01
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,521
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12681630
Author URL: https://archiveofourown.org/users/Kendrickhier/pseuds/Kendrickhier
Summary: After discovering Krypton is in peril, rather than wasting her time trying to fix it herself or trying to convince the (weak-willed) people to take action, Astra thinks of a rather unorthodox solution: calling a demon for help. The price of her favor is not what she expects it to be.





	What to Do with a Demon

**Author's Note:**

> That’s right, the 666th General Danvers fic is a demon AU by yours truly, because I could not resist :D Enjoy, I hope!

“Alexandra, Heir to Hell, I call upon thee.”

The words ring out in an ancient language the summoner is not aware of, the syllables clumsy at best from a voice that is not used to such sounds, unaware even of the meaning of the words, relying on phonetics that were spelled out in the book. There is only one thing she knows; these words were supposed to call upon a demon that could help with her problem, should it be interested in what she had to offer in exchange for such a deal.

Krypton was in peril, put very mildly. Astra discovered that after her latest missions when many immaculate calculations did not accurately predict where she would find herself. She’d taken it as a sign of something being wrong, and rightfully so; the core had gotten unstable after the draining of too many resources.

Instead of stepping to the Council as she should have however she’d found herself in her office with a book, left on her desk for her to find with a note. ‘A gift for times in need’ it had read in the same dreadful language the book had been written in: English.

She doesn’t think her old tutors would have guessed she’d one day have to call upon her knowledge of that particular language for necromancy of all things. Perhaps for a human invasion, or for a more friendly first contact with the curious beings, but not summoning a demon. Nonetheless that is what she is doing right now.

Well, what she is _trying_ to do. For the moment this supposed demon is remaining unresponsive, which makes her doubt the credibility of this ritual.

Shaking off that thought, Astra calls out again, refusing to give up this easily; perhaps the first time she’d simply made a mistake in pronouncing it, or maybe it is meant to be chanted rather than spoken once. She hasn’t read anything about it in that old human book, but then it hadn’t been particularly exact and specific about a great many things.

“Yeah, yeah, I heard you the first time. No patience these days,” a voice grumbles out of thin air, lacking a visible entity it belongs to. The words are spoken in Kryptonese and while Astra didn’t anticipate that, she’s pleasantly surprised. Another pleasant surprise is the quality of the voice: a similar pitch to her own, feminine, and more importantly lacking any echoes or growling the humans claimed it would have.

It is silent for a few moments, before an eruption of a blue flame comes from the center of her pentagram, reaching up to the high ceilings. The suddenness has Astra stumbling back a couple of steps, startled. This was not a thing she’d expected—she’d been prepared to face something that would be classified as a monster, she’d been prepared to bite back her response to whatever its appearance was, but glorified pyrotechnics had not been on the list of things she’d anticipated.

The flames die down and a silhouette of what looks like a woman appears as soon as they do, like a phoenix rising from its ashes. The more it diminishes, the more Astra can see of the being, and it’s unmistakable that she looks just like a Kryptonian, clad in a burgundy robe that looks like it could be from her own planet if it weren’t for the ragged material and worn edges. Brown hair is revealed, chopped of below her jawline, giving it a sharp edge. Red eyes meet her own green ones, emanating a dim red glow that add to the imposing air surrounding her, but Astra refuses to be intimidated even by a demon and she keeps their gazes locked, taking on her own commandeering poise.

The demon smirks at the determination, before taking her time to look at her environment at last, gaze sticking to the pattern on the floor. “I must admit I’m impressed. This is the best pentagram I’ve seen in centuries, perhaps even millennia. You actually got the angles right, consistently.”

She steps towards the edge of the pentagram’s circle which is surrounded by another circle filled with runes, experimentally reaching out a hand, which Astra watches with suspicion. Immediately the hand retracts, fingertips now appearing charred, and Astra releases a relieved breath; it’s functional, and it should keep the demon both trapped and truthful.

Alexandra continues while examining her fingertips, and Astra swears this hellish creature is actually _pouting_. “Wish you’d have slacked on the runes a little though. No human has ever done them properly before.” Sentence finished, she flicks a thumb over her fingertips and the charcoal scrapes off her skin with the motion easily, restored like it was never there.

“I’m no human,” Astra proclaims, straightening with the surge of pride that came from evidently being the first to succeed, and mildly insulted by the mere idea of being seen as anything but Kryptonian.

“You aren’t,” the being agrees. “Which is a first. What planet is this?”

Furrowing her brows, Astra wonders briefly at how Alexandra appears to be speaking her language when she isn’t aware of what planet they’re on, before brushing it off as some convenient supernatural gift. “We’re on Krypton,” she states, frown remaining in place. “But I didn’t call you here to answer your questions.”

Alexandra smiles, “Straight to the point then? Have it your way, what is it you want?”

“I want my planet saved. To have its damage undone so it will not perish.”

“A selfless request?” She sounds genuinely surprised, the raised eyebrows only confirming that point. “You really are different. Alright, you’re aware of the price?”

Astra nods; the book had warned a demon would always be out for your soul and thus to be careful with your wishes. “It is worth it.”

“A deal it is,” Alexandra nods in turn. “Consider your planet saved.” The demon smiles, a genuinely kind gesture, before her red eyes light up intensely, the glow appearing to fill the entire room—perhaps even beyond that, because the solid red color is all Astra can see at the moment, maybe the entirety of reality is bathed in this inescapable red light—before it fades, and Alexandra’s eyes dim to a brown instead.

When she gathers her bearings, Astra frowns; nothing seems to have changed upon first glance, and on top of that she herself is still here, inside her body and decidedly alive, with a smiling demon in front of her. “I don’t understand.”

Laughter. This demon has the gal to actually laugh at her confusion, but Astra can’t bring herself to be upset about it for long, because hell if that isn’t one of the most beautiful sounds she has ever heard. “Did you think I would kill you, you silly Kryptonian?”

“Yes? My soul—“

“Is bound to me,” she intercepts. “Eternity gets lonely, you know? Sure, I have my legions, but they don’t actually like me very much, so this is the only way to get a companionship.”

“A companionship?” Astra gapes at her. “You saved an entire planet and all you want in return is companionship?”

Alexandra grins, sharp incisors gleaming against Rao’s red light, and it would be charming if it didn’t make her look so dangerous. It’s still strangely endearing to Astra, however. “Well, more is certainly on the table.”

Scowling, Astra points out, “I have a husband.”

“So?”

“I resent the implication,” she says with narrowed eyes, before realizing something. “What exactly did you do?”

“Shouldn’t you have asked that _before_ making a deal with me?” Alexandra questions, amused.

A glare is all the answer she gets.

“I changed reality. As far as everyone else is concerned, Krypton has never been anything but healthy.”

Astra nods, the information processing surprisingly easily considering how mind-boggling the power to shift reality is, before following up, “And what exactly does it mean to have my soul _bound_ to you?”

“Essentially? You’re stuck with me for the rest of your life. I go where you go.” Alexandra smirks. “Which also means you’ll have to let me out of here at some point, or you’ll be as trapped in this vicinity as I am.”

That is a little harder to process, and she’s already agonizing over the impracticality of the concept of being _stuck_ together. There is an implication of there being a maximum amount of space they are capable of being apart, which will make private endeavors considerably harder.

“Don’t worry, I know how to make myself scarce when necessary. Invisibility is a nice perk.”

It’s slightly unnerving how Alexandra appeared to know what she was thinking about, but it’s reassuring; that solves some of the issues. It still doesn’t solve the fact that she’ll expose her _family_ to a demonic trickster however, nor does it solve how to explain Alexandra’s sudden appearance to people. She can’t very well try to hide her. “What do I tell Non regarding your presence?”

“You could tell him the truth?”

\-----

The truth, as it turned out, only led to more questions, which eventually led to disbelief; surely Krypton was fine, it’s always been fine and will always be fine. According to Non, anyway, and nothing could convince him otherwise. He did, at least, seem to accept Astra was now stuck with a demon to her side, though only after rigorous testing.

Luckily that does mean Astra is now aware of the exact range she has when it comes to Alexandra; outside of it, well, it’s like running into an invisible wall, a visual that had amused Non greatly.

(He later paid for that amusement when an invisible Alexandra kept trying to trip him, eventually succeeding with the peel of some fruit unbeknownst to Krypton. Astra couldn’t help the laughter that bubbled up at that hilarious sight.)

The information regarding how far she could leave Alexandra’s side was good to have, because she did not want the demon anywhere near Kara, friendly as she may currently appear. After making the proper calculations with the help of a blueprint of their apartment, she pinpointed the exact point to trap Alex; the closet of their sleeping quarters. That way she could reach almost the entirely of the house, from the front door to the kitchen, with the exception of the back cabinets in said kitchen. That could be worked around, however.

So naturally that is exactly what she would do every time her little one came for a visit, with or without Alura and Zor-El.

“Get in,” she demands, pointing to the emptied closet.

“Seriously? You’re going to trap me again?”

Astra’d trapped her multiple times already, though this was the first time it concerned Kara. Building trust with a being supposedly inherently evil didn’t come without some level of restrain, in Astra’s mind.

“I’ll stay out of sight if you want me to,” Alexandra continued, almost pleading. “There’s no need for this.”

Astra was not about to let up however, gritting her teeth. “I said, get in.”

Frowning, Alexandra crossed her arms defiantly. “I’m sorry, did I miss the part where I’m indebted to you somehow?”

“Listen.” Glowering, Astra closes in on her threateningly. “I don’t care if you are some kind of ancient demon, I will not have you come close to my little one. If you touch her I _will_ find a way to destroy you, am I clear?”

“Good luck with that,” Alexandra says, trying to keep that defiant attitude, to remain unaffected, but her eyes betray how hurt she is by the hostile statement and blatant mistrust, and Astra hates seeing the effects of her words, but she cannot retract it. Kara’s presence is announced soon after and Alex resigns herself to the closet, gesturing for her to go ahead, and the seal is on the door before she can think better of it.

\-----

Alexandra hasn’t stopped pulling pranks on Non, much to his chagrin, something Astra has just written off as part of the demon’s nature at this point. The results merely amuse her, with an added feeling of relief that she was not the target of their domestic trickster.

Non is not quite as amused as she is however, and when he sits down on his chair at the table for their evening meal together, a fart noise resounding from below him, he’d had enough. He glares at Alexandra, who looks rather smug, while Astra is desperately fighting the urge to laugh.

“That’s it!” He bellows, immediately rising from his seat, taking the foreign object from the chair and smacking the cushion on the table. “I will not tolerate this any longer, Astra. Either this demon leaves, or I do.”

The need to laugh dies as abruptly as his snapping, and Astra frowns. “You know I can’t send her away, Non. She goes where I go.”

Pinching the bridge of his nose at the reminder, Non lets out a sigh, sound more reasonable now that he’s recomposed. “Then trap her elsewhere, like when your niece is here.” He gestures vaguely in the direction of their sleeping quarters. “Or command her to disappear from sight—mine, at the very least.”

For a moment Astra considers this—the invisibility, not the trapping, they have passed that point with the exception of situations that concern Kara; even now that she undoubtedly trusts her, she is not willing to expose Kara to a demon.

However then she turns to Alex, who looks somewhat wounded as the silence lingers on. The opacity of her body is decreasing and increasing, flickering between that invisible state Non desire her to be in and the visible state that she herself prefers to be in. Frowning, Astra reaches over to her hand and holds onto it firmly, before returning her attention to Non. “No,” she tells him, much to his astonishment. “I will not degrade her in such a manner. She has as much right to be here as we have.”

Alexandra stops flickering, fully visible and visibly just as thrown as Non is at the certainty of her words. A few beats of silence pass, and a few more, until Non gathers himself and dips his head. Then he turns and takes his leave.

Astra sighs, calling after him, “Non, don’t be like this.” It does not stop him in his tracks however, and she shakes her head at his stubborn pride. She didn’t notice when she exactly she started tightening her hold on Alexandra’s hand, but she lets her white knuckles slacken now.

When she looks back at Alexandra there are unshed tears in her eyes, ones she is clearly ignoring, and it makes Astra’s heart clench in sympathy, squeezing her hand softly. “I’m sorry about him. Are you alright?”

Alexandra shakes her head—Astra’s heart clenches even harder—before she speaks. “You stood up for me,” she says, and she sounds a little breathless.

That wasn’t what Astra’d expected to hear, and she isn’t sure how to respond, because she doesn’t understand why that would make Alexandra emotional. “Of course, he was way out of line.”

Alexandra laughs, a disbelieving thing. “In all my years, demon or otherwise…” She shakes her head. “Thanks.”

Things click into place in her mind now, and Astra is hit with a sudden understanding. The implication is loud and clear; no one’s ever defended Alexandra before, not even in her human life. Once again her heart clenches painfully in her chest, and Astra’s expression softens. “You’re welcome, Alexandra.”

“Please, it’s Alex.”

\-----

“Aunt Astra, may I have a Manderian cloudcake?”

Astra smiles at the young Kara, “Of course, little one. Upper left shelf.” She can’t deny her niece anything, much less something she keeps in stock for her especially, as they are her favorite.

Kara lights up in response and dashes off towards the kitchen like an enthusiastic child—which she is, but it’s easily forgotten when they talk about quantum mechanics and high science even Astra can only barely wrap her head around. Astra has never considered herself unintelligent, but she almost feels like it when listening to Kara, something that couldn’t make her prouder.

Alex is once again locked in the closet with her niece visiting, the three of them being the only ones in the apartment now that Non’s left. Locking the demon up for these visits has become something of a habit, and Alex is no longer insulted by the ordeal now that she understands her motivations and protectiveness of her niece, after the many stories Astra’s told her.

For some reason being let out of the closet never fails to amuse Alex, though she refuses to explain why. It’s far from the only thing that amuses the previously Earth-bound demon without Astra understanding it, but it’s something that stands out, leaving her wondering. Did they have some sort of ritual surrounding closets back on that primitive planet? Or was it related to her demon-hood?

“Where is the step-stool?” Kara’s voice resounds from the kitchen, bringing her back to reality from her thoughts. “I can’t reach the cloudcakes!”

Cursing under her breath, she realizes the infernal thing broke not too long ago and hadn’t been replaced yet. It had slipped her mind completely, what with the drama of Non moving out of their apartment and appearing to have permanently settled with his brother and respective sister-in-law. “I’ll be there in a moment, Kara!” She responds, already loathing what she’s about to do; they’re alone, and of course she’d stored the cloudcakes on the shelves in the back of the kitchen, outside of the demon’s range.

Somewhat reluctantly, Astra gets to their sleeping quarters—her sleeping quarters, no longer Non’s, though Alex has been keeping her company in his stead, upgraded from her mattress on the floor—and breaks the seal on the closet door, revealing an astonished Alex.

“Isn’t Kara still here?”

“Yes.”

“… And you’re letting me out?”

Astra sighs. Truthfully she’d rather stick to her principle of not exposing Kara to a demon, but there’s no real reason beyond that any longer; she trusts Alex now, fully and without hesitation. “I’d prefer if you remained out of sight, but yes. I need something from the kitchen.”

She nods. “No touching her,” she reaffirms before Astra can do so. “I’ll behave.”

There’s a twinkle in her eyes that makes Astra believe their ideas of ‘behaving’ differ somewhat, but it’s sincere enough that she accepts it with a nod of her own and turns to make her way to the kitchen.

Alex once again snickers when she comes out of the closet, murmuring something in a language she’s never heard before—which is a first when it comes to the demon, who’s explained she’s usually speaking in a language that is universally understood—but is clearly some sort of inside joke. Astra doesn’t ask; she notices it, but it’s not relevant to her.

She enters the kitchen first and smiles at the sight of a near-pouting Kara, who seems to perk up a little at her presence. “Let’s get you a cloudcake, shall we?”

When she’s reaching out for the container of them, Kara gasps, and Astra nearly groans, because there’s only one conceivable reason for such a reaction: Alex has entered the kitchen.

Visibly.

“Who are you?” Her little niece sounds so suspicious and even protective, Astra momentarily forgets her annoyance at the surge of warms that protectiveness over her prompts, long enough to grab the entire box and close the cabinet again.

Alex doesn’t answer, instead throwing an expectant look at Astra, which causes Kara to look at her in turn. How is she going to explain this? She is absolutely not going to tell her niece she made a deal with a demon. “This is Alex. Alex, this is my niece, Kara, who I’ve been telling you about.”

“It’s nice to meet you, Kara,” she says after she looks back at the child, a warm smile on her face that makes Astra’s heart stutter. This is a new shade on Alex, a sincere affection she hasn’t seen on her face before.

What Astra doesn’t know is that Alex has been looking at her with a similar affection whenever she isn’t looking, nights spent next to each other in particular.

However, Kara frowns at her, the suspicion not leaving her, and it’s impressively intimidating for someone so young.

Astra recognizes that facial expression from Alura, so clearly her sister’s child, but her posture, that isn’t emulated from her sister, that is something she’s clearly taken from Astra herself, a fact that warms her heart with a proud affection. Alex shifts under the scrutiny, though she guesses the discomfort is played up, for she can’t imagine an actual demon to be intimidated by this.

Kara turns to her aunt then however, the intensity in her gaze not letting up. “Is this why uncle Non left? Have you found a better suitor?”

The question throws Astra. She opens her mouth to say something, anything, but found no satisfactory explanations, instead closing her mouth again. Does Kara think she’s betrayed Non? She supposes she has in a way, but not a way that is traditional in any sense; she’s most decidedly chosen Alex over Non, and Non certainly had left because of her choice, but this has nothing to do with whether or not Alex is considered a suitor.

Which she isn’t.

Which she shouldn’t be.

She’s a demon.

“I needed a place to stay and your aunt was kind enough to let me stay with her,” Alex mercifully responds after several moments of silence. “A courtesy for a friend, simple as that.”

Kara’s skepticism does not let up and she keeps eyeing Alex, like she knows something is off, before she shrugs it off and seems to accept it, turning back to Astra with somewhat of a frown. “Why didn’t you tell me you had a guest? She would have missed out on the cloudcakes!”

Astra blinks, thrown yet again, when Kara breaks out into a grin to indicate the sudden lightheartedness of her statement, and Astra follows along easily, chuckling her relief. Crisis averted. “You’re right, that would have been rude of me.” She looks at Alex. “Want one?”

Grinning, Alex counters, “Two, and I’ll forget about almost missing out earlier.”

Shaking her head, she hands Kara the container. “Take these to the living quarters for us, will you?” With an excited nod, Kara is off as quickly as she snatches it from her hands, and Astra knows her niece will find a way to sneak an extra cloudcake, which she’ll pretend she doesn’t know about, or noticed at all.

It gives her the chance to face Alex alone though, and Astra smiles gratefully at her. “Thank you.”

“Not a problem,” Alex brushes off, before grinning mischievously, that same sharp toothed grin from when she’d first been summoned. “Though I would not have complained had you confirmed her suspicions. There are worse things to be than your ‘suitor’.”

Astra barks out a laugh and prods Alex with an elbow as she passes. “Keep dreaming, Alex.” Astra can practically feel Alex’s gaze on her when she walks away, and if she puts a little extra sway in her step to actually give her something to dream about, well, she won’t admit to it.

The slight sputtering behind her tells her she’s succeeded, though.

\-----

Now that Non is no longer living with them, time spent at home now usually involves interacting with Alex in one way or another, provided she’s not studying something. They talk frequently, about Astra’s life and why she chose to join the military guild, about Alex’s former human life and the sister she used to be so protective of, but also about her afterlife as a demon: how she gathered her legions and why they dislike her so much.

Turns out these legions are comprised of bound souls, much like Astra, though unlike her they have been ripped from their lives prematurely. Astra still isn’t sure what sets her apart from them—Alex remains rather vague about it, or avoids the question entirely—but at the very least she’s discovered that her fate is now tied to them, fated to be part of those troops after her long life ends.

At least she’ll still be a warrior; altogether it doesn’t sound too bad to her.

Alex’s apparent favoritism doesn’t leave her mind though, and one day when they are settled on the couch together, the actions of the months spent together start to make sense to her. “You were jealous,” Astra announces suddenly, breaking the companionable silence they’d found themselves in.

“What?”

“That’s why you played tricks on Non,” she continues, “Jealousy.”

Alex scoffs. “That’s ridiculous, no way. I’m an immortal demon, I can get anything I want any time I want. I am not _jealous_ of some mortal.” The demon is rambling, and the tips of her ears have reddened slightly, two things that give her away rather obviously.

Grinning devilishly, Astra doesn’t let up. “Oh, but you got what you wanted, didn’t you? He left of his own accord, you even had me defend you.”

She can see Alex’s throat work as she swallows, and Astra revels in the lack of composure she’s caused. To add to it she moves, throwing a leg over Alex’s and settles on her lap, leaning over her. “I’m not blind, Alex.”

Astra remembers the looks Alex has thrown her, even before Non left, lingering too long for her not to notice and being fully aware of what they meant. “If there is something you want,” Astra says as she leans in, closing in on her face until they are only several inches apart, “Ask.”

“I…” Alex wants to speak, but the close proximity clearly hasn’t helped her coherence; she looks a little shellshocked. A moment later something sparks and she regains some composure, a determination reflecting in her eyes before she speaks. “Astra, would you be—“ She doesn’t finish that sentence, seeming to think better of it, restarting, “Would you kiss me?”

Smiling, Astra closes the small distance between them, kissing her without hesitation. She’s known this was coming if she would let it, and she certainly does not regret letting it upon the feeling of those soft warm lips against hers. Lips that part, an even warmer tongue poking between them, searching for her, and Astra responds in kind.

A soft moan escapes her when Alex sucks on her bottom lip, surprisingly blunt teeth grazing, before they nip playfully, and Astra wishes she didn’t have to break away when Alex’s tongue soothes the dull sting she’s left. That dreadful need for air causes her to have to do so anyway, and when she pulls back, she rests her forehead against Alex’s, sharing her breath.

When Alex asks for another kiss Astra obliges all too happily and, she thinks as their tongues are intertwined, if Alex were to ask for anything more defining and permanent, she’d agree to it just as readily.

She _is_ spending the rest of her life with that demon, after all.

**Author's Note:**

> And they live a long and satisfying life together (as well as an even longer and equally satisfying afterlife). The end. As far as you can call eternity together an ending :P


End file.
